LAGOS (Reuters) - An outbreak of Lassa fever, a viral hemorrhagic illness, has killed 110 people this year in Nigeria in an “unprecedented” outbreak that has hit half of the states in Africa’s most populous nation, its disease control agency said on Wednesday.

It is mainly transmitted to humans via contact with food or household items contaminated with rodent urine or excrement.

Symptoms of the virus - which can also be passed between people through bodily fluids of those infected - include fever, headaches and, in the most severe cases, death.

In a situation report dated March 4, the Nigeria Centre for Disease Control identified 1,121 suspected cases, of which 353 were confirmed positive, eight were probable and 723 were negative. A further 37 cases were awaiting laboratory test results.

Last week the World Health Organization said there had been 1,081 suspected cases and 90 deaths reported from 18 of Nigeria’s 36 states. Centres to manage the outbreak had been set up in four states, it said.

Nigeria, which has some 190 million inhabitants, has the biggest economy in Africa.

The disease is also endemic in Ghana, Guinea, Mali, Benin, Liberia, Sierra Leone and Togo, according to the WHO.